Stilbene analogues

Cells from tissues associated with primary and secondary sexual characteristics are under particular endocrine control. Sex hormones determinethe growth, differentiation, and proliferation of such cells. When a tumor develops in such tissues, it is sometimes hormone dependent and the use of anti hormones removes the impetus for the tumor s headlong growth. Many nonsteroidal compounds have estrogenic activity diethylstilbest-jrol (81) may be taken as an example. Certain more bulky an- 

Nitromifene (85) is such an agent. A Grignard reaction of aryl ether and ketone leads to tertiary carbinol Tosic acid dehydration leads to a mixture of 1 and stilbenes which constitute the antiestrogen, nitromi fene (85) 

Another example is tamoxifen (89). Its synthesis begins with Grignard addition of reagent to aryl ketone giving carbinol Dehydration leads to the readily separable and 

Netherlands Patent, 6,605,452 (1962) Chem. Abstr., 104914e (1967). 

Lednicer and L. A. Mitscher, The Organic Chemistry of Drug Synthesis, Vol. 2, Wiley, New York, 1980, p. 81. 

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The objective of this article is to review critically the bimolecular photochemical reactions of the stilbenes. While the emphasis will be placed upon the unsubstituted stilbenes t-1 and and c-1, comparisons with substituted stilbenes and stilbene analogues will be made in some cases. In most of the reactions that will be described, the reactive excited state is the lowest singlet of t-1, - -t. Because of the short lifetime of It, unimolecular processes (fluorescence and trans-cis isomerization) can compete with bimolecular reactions under normal reaction conditions. While competing unimolecular processes are... 

The fluorescence Intensity of substituted stilbenes and stilbene analogues provides a useful indicator of photochemical reactivity. Virtually all of the reported bimolecular photochemical reactions of electronically excited stilbenes involve stilbenes which are fluorescent at room temperature in solution. The absence of fluorescence is indicative of a singlet lifetime too short (< 100 ps) to allow for efficient bimolecular quenching. 

The observation of triplet sensitized cycloaddition reactions of 10 but not t-1 with vinyl ethers reflects the requirement of a planar stilbene excited state for effective interaction with ground state electron-rich or electron-poor alkenes. While triplet sensitized reactions of other cyclic stilbene analogues (e.g., 5-9) have not been reported, it appears quite likely that they should occur. 

Recently, synthesis and investigation of stilbene analogues containing a crown ether fragment were developed [30,31] (Scheme 9). 

All of these control experiments are consistent with a mechanism in which the stilbenes 5 are in dynamic equilibrium with the equivalent benzylic alcohols 4 and the oxidative-cleavage reaction occurs on the latter. This equilibrium explains 1) the observed requirement for water for the stilbene oxidations 2) the unsymmetrical product distribution from both the alcohols and stilbenes and 3) the enhanced reaction rate of the chlorobenzyl alcohol 4b as compared to the stilbene analogue 5b at 120 °C. 

Carbazole-containing stilbene analogues have been shown to be efficient two-photon absorbing chromophores <2000TL8573>. 

A study of the photochromic behaviour of the stilbene analogue (103) and its reversible cyclization to (104) has been made. ... 

Topics which have formed the subjects of reviews this year include theoretical studies of the photochemistry of thiiranes, photoaddition of amines to aryl olefins and arenes, the synthesis of heterocyclic compounds, photoamination directed towards the synthesis of heterocycles, selective addition of organic dichalcogenides to carbon-carbon unsaturated bonds, photocyclisation mechanisms of c/5-stilbene analogues, synthetic utility of the photocyclisation of aryl-and heteroarylpropenoic acids, photochromic diarylethenes, spiropyrans, cy-clophanes, and polycondensed aromatics," photochromic organic media, photophysics and photochemistry of P-carbolines, and the photochemical synthesis of macrocycles.Chirality switching by light has also been described. ... 

Photocyclization of haloarenes into heterocycles 81CSR181. Photocyclization of stilbene analogues with formation of condensed... 

TABLE 16a Absorption Maximum and Lifetime of the Triplet of Stilbene Analogues in Glassy Media"... 

Y. Cbun (2002). Design, synthesis, and discovery of novel frans-stilbene analogues as potent and selective human cytoehrome P450 IBl inhibitors. J. Med. Chem. 45, 160-164. 

Thakkar, K., Geahlen, R.L. and Cushman, M. (1993) Synthesis and protein-tyrosine kinase inhibitory activity of polyhydroxylated stilbene analogues of piceatarmol. J. Med. Chem. 36 2950-2955. 

The role of central bond torsion in nonvertical triplet excitation transfer to stilbenes, an example of stilbene analogues, biindanylidenes, was recently discussed... 

Resveratrol (2.1) was used as the prototype compound to synthesize trans- and c/s-stilbene analogues. The compounds are grouped according to their cytotoxicity. The IC50 for compounds in each group is Croup 1, >100pM Croup 2, 20-80pM Croup 3, 2-lOpM ... 

The two-photon absorption technique was applied for investigating cross-linked polyurethane containing modifled stilbene as potential frequency doubling or electro-optical controlling devices [38], properties of some donor-acceptor molecules with stilbene and azobenzene molecules as backbone [39], 4-fluorophenylethynyl-and 4-nitro-( )-stilbenylethynylruthenium complexes [40], series donor-acceptor stilbene analogues [41], and so on. 

Baker and Sims have shown that addition of a catalytic quantity of 15-crown-5 to a Wadsworth-Emmons reaction greatly facilitates olefin formation. For example, reaction between the aldehyde (31), phosphonate (32), and sodium hydride in the presence of 15-crown-5 gave the heterocyclic stilbene analogue (33) (45% the key step in a synthesis of the furanosesquiterpene pallescensin-E). ... 

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